There are some tar sand systems that are successful in making SCO, such as those in the Canadian Athabasca tar sand area that surface mine and process the tar sands, where they first separate sand (85%) from bitumen (15%) to avoid processing the sand in the reaction systems. The separated bitumen is converted to sweet, light crude oil by conventional refinery type operation. Separation of the sand from the bitumen requires beneficiating operations such as floatation cells and secondary separation equipment and processing and equipment to prepare the tar sand for flotation. Tailing oil recovery is necessary to clear the sand for disposal, however the sand is not completely cleared of bitumen.
Existing technology uses a large number of physical and chemical processing units for the treatment of wet tar sands, e.g., fluid cokers, LC finer, tumblers (being phased out by hydro-pumping), beneficiation including: primary separation vessels with floatation cells and secondary separation systems necessary to recover the bitumen from the tar sand; tailing oil recovery systems which result from the sand not being completely cleared of bitumen; tailing settling ponds which are necessary to settle and separate fine clays and other undesirable solids from the water required for floatation since the water must be reused to maximize clean-up to reduce environmental problems. These systems require large facilities along with the maintenance and reclamation required.
For example, U.S. Pat. Nos. 5,340,467 and 5,316,467 to Gregoli, et al. relate to the recovery of hydrocarbons (bitumen) from tar sands. In the Gregoli, et al. patent process, tar sand is slurried with water and a chemical additive and then sent to a separation system. The bitumen recovery from tar sand processes described in U.S. Pat. Nos. 5,143,598 to Graham et al. and 4,474,616 to Smith, et al. also involve the formation of aqueous slurries. Other processes involving slurries, digestion, or extraction processes are taught in U.S. Pat. Nos. 4,098,674 to Rammler, et al., 4,036,732 to Irani, et al., 4,409,090 to Hanson, et al., 4,456,536 to Lorenz, et al. and Miller, et al.
In situ processing of tar sand is also known as seen from the teachings of U.S. Pat. Nos. 4,140,179, 4,301,865 and 4,457,365 to Kasevich, et al. and 3,680,634 to Peacock, et al.
U.S. Pat. No. 4,094,767 to Gifford relates to fluidized bed retorting of tar sands. In the process disclosed by the Gifford patent, raw tar sand is treated in a fluidized bed reactor in the presence of a reducing environment, steam, recycle gases and combustion gases. The conversion of the bitumen, according to the Gifford patent, is through vaporization and cracking, thereby leaving a coked sand product. The steam and oxygen, according to Gifford are "injected into the fluidized bed in the decoking area above the spent sand cooling zone, and below the input area in the cracking zone for fresh tar sand."
The process and apparatus of the present invention avoid the use of the large number of physical and chemical processing units used in the processing of wet tar sand by using a single continuous reactor system to hydrocrack and hydrogenate the dry tar sand. Moreover, because the present invention directly hydrogenates dry tar sand, larger quantities of valuable sweet, light crude oil is obtained. Moreover, with the present invention, less gas and substantially no coke is produced.